The only main difference many brewers still agree on is the kind of malt that should be used to brew each type of beer. Porters use malted barley and stouts are primarily made from unmalted roasted barley, which is where the coffee flavor most people associate with stout comes from. But even these rules seem to be somewhat blurry according to brewers. “My approach to a stout would be to use a larger percentage of roasted barley,” Wayne Wambles of the celebrated Cigar City Brewing tells CBB. “I subscribe to the never say never camp, though, so I can’t say that I would never put roasted barley in a porter. Under certain circumstances, I would consider it.”

via The Difference Between Porter And Stout Beer: It’s Complicated | VinePair.